Low-cost and high-strength plastic-wood composite material and preparation method thereof

Abstract

The invention relates to a low-cost and high-strength plastic-wood composite material and a preparation method thereof. The low-cost and high-strength plastic-wood composite material is prepared from raw materials including high-density polyethylene, high-toughness polyester resin, maleic anhydride grafted polyethylene, a Teflon high-temperature cloth fiber material obtained through surface treatment, a small amount of wood flour, a flame-retardant filler, a coupling agent and other auxiliaries through granulation and extrusion molding. The Teflon high-temperature cloth fiber material obtained through surface treatment is a fiber material with the length of 1-2 cm obtained by cutting, crushing and filtering Teflon high-temperature cloth leftover materials through a filter screen, and the fiber material with excellent binding force is obtained through chemical treatment. The Teflon high-temperature cloth leftover material is used in the plastic-wood composite material, the finally obtained plastic-wood composite material is high in static bending intensity, excellent in flame retardance and mildew resistance and low in cost, and comprehensive utilization of the Teflon high-temperature cloth leftover material is achieved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a low-cost, high-strength wood-plastic composite material and its preparation method. Background Technology

[0002] With social development and the improvement of people's living standards, wood-plastic composites (WPCs) are increasingly used outdoors due to their aesthetic appeal and durability, such as in pavilion beams and long-span flooring. However, traditional first-generation WPCs, made primarily from wood flour, calcium carbonate filler, and polyethylene, have the advantages of simple and efficient manufacturing processes. However, the high wood flour content (around 60%) makes them prone to moisture absorption and mold growth outdoors, and they are also flammable, resulting in low safety levels. Furthermore, their static bending strength is low, making them susceptible to deformation and unsuitable for applications with large spans (over 30cm). To address these issues, especially moisture absorption and mold growth, many manufacturers now use second-generation WPCs, also known as co-extruded WPC composites. This involves co-extruded a layer of polyethylene plastic onto the surface of the first-generation WPC to isolate water and reduce mold growth, resulting in a co-extruded wood-plastic composite material. For example, ZL201510427616.1 discloses a co-extruded wood-plastic composite material. Compared to first-generation wood-plastic composites, second-generation co-extruded wood-plastic composites have added a co-extrusion process, which significantly increases the cost of raw materials and processes, as well as the difficulty of production control. However, it is also difficult to solve the problems of easy combustion and low strength.

[0003] Teflon high-temperature cloth is a special composite material made by impregnating medium-alkali glass fiber cloth with Teflon emulsion (polytetrafluoroethylene emulsion) and then sintering it at high temperatures. It is non-flammable, high-temperature resistant, and hydrophobic. Due to the non-flammable, high-temperature resistant, corrosion-resistant, non-stick, and hydrophobic properties of the Teflon coating, Teflon high-temperature cloth is widely used in food processing and pharmaceutical industries for non-stick conveyor belts, such as baking mats, microwave drying belts, and baking tray mats; it is also used in chemical equipment for high-temperature resistance and corrosion protection, and as insulation material for electrical equipment. However, because Teflon high-temperature cloth products need to be cut and processed according to customer size requirements when sold externally, the industry generates a large amount of waste Teflon high-temperature cloth scraps of varying sizes, exceeding 20,000 tons annually. This makes it difficult to handle and utilize, and currently it is mainly treated as waste and decomposed in high-temperature furnaces (at temperatures above 700℃), wasting a large amount of energy and resources. Furthermore, the high-temperature decomposition process also generates a large amount of harmful exhaust gases that need to be treated, posing a significant obstacle to the industry's development. How to achieve high-value-added comprehensive utilization of this material is a major challenge for the industry. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a low-cost, high-strength wood-plastic composite material. This wood-plastic composite material is obtained by granulation and extrusion molding of raw materials including high-density polyethylene, high-toughness polyester resin, maleic anhydride-grafted polyethylene, surface-treated Teflon high-temperature cloth fiber material, a small amount of wood flour, flame-retardant filler, coupling agent, and other additives. The surface-treated Teflon high-temperature cloth fiber material is obtained by cutting, crushing, and filtering Teflon high-temperature cloth scraps to obtain glass fiber material containing Teflon fibers with a length of 1-2 cm. Its main components are medium-alkali glass fibers (90-93%) and a small amount of Teflon fibers (7-10%). It is then chemically treated with a specially prepared adhesive to obtain a fiber material with excellent bonding strength.

[0005] A low-cost, high-strength wood-plastic composite material, wherein the raw materials comprise, by weight: 22-27 parts of high-density polyethylene; 4-5 parts of high-toughness polyester resin; 8-10 parts of maleic anhydride-grafted polyethylene; 14-18 parts wood flour; 45-51 parts of surface-treated Teflon high-temperature cloth fiber; 4-8 parts of flame-retardant filler; 0.5-0.8 parts of coupling agent; 3-4 parts lubricant; It also includes melamine, a flame-retardant crosslinking aid, used at a dosage of 0.3-0.5% of the Teflon high-temperature fabric fiber mass; melamine, a flame-retardant and reinforcing crosslinking aid, can be ground into fine powder with a particle size controlled at 200-250 mesh before use; the lubricant is oxidized polyethylene wax with a melting point of 94-100℃ (e.g., model PEWO-0520, purchased from Nanjing Tianshi New Material Technology Co., Ltd.); The raw materials may also include other additives as appropriate. Other additives may include: antioxidants (e.g., antioxidant 1010), ultraviolet absorbers (e.g., UV-329), etc., with each in a mass fraction of 0.3-0.5 parts.

[0006] The Teflon high-temperature cloth fiber material obtained through surface treatment is a glass fiber material containing Teflon fibers with a length of 1-2cm obtained by cutting, crushing and filtering Teflon high-temperature cloth scraps. Its main components are medium-alkali glass fibers (accounting for 90-93%) and a small amount of Teflon fibers (7-10%). It is then chemically treated with a specially prepared adhesive to obtain a fiber material with excellent bonding strength. The adhesive product used in this invention addresses the problem that Teflon high-temperature fabric fibers, due to their Teflon fiber content, have insufficient bonding strength with conventional adhesives and are prone to cracking. This invention creatively uses bisphenol A diglycidyl ether, N-(3-aminopropyl)-N-methyl-1,3-propanediamine, triglycidyl isocyanurate, and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane to synthesize and extend a semi-finished product, which is then compounded with E-20 epoxy resin and the epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane to form the final product. The high nitrogen content in this adhesive molecule not only enhances its flame retardant properties, but the presence of amino groups also strengthens the bond between the adhesive and Teflon fibers. The chain extension of triglycidyl isocyanate and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane increases the epoxy density of the adhesive, while E-20 epoxy resin modifies the toughness of the adhesive. The participation of the epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane enhances the wetting and bonding properties between the adhesive and the Teflon fiber surface.

[0007] Specifically, the preparation method of surface-treated Teflon high-temperature cloth fibers is as follows: Waste scraps of Teflon high-temperature cloth are first cut into sheets less than 10cm in length and width, then crushed using a crusher and filtered through a filter to obtain short fiber materials with a length of 1-2cm and a fiber diameter of 8-15μm; these are then chemically treated. The chemical treatment method is as follows: (1) Preparation of adhesive: In the case of a small amount of Teflon fiber (5-8%) on the surface of Teflon high temperature cloth fiber, it is necessary to use an adhesive component with excellent bonding force to treat the fiber surface so that it can be fully bonded and molded with wood flour, polyethylene plastic, etc., so as to prevent the wood-plastic composite material from cracking.

[0008] The prescribed amounts of bisphenol A diglycidyl ether and catalyst were dissolved in ethylene glycol monomethyl ether. Then, N-(3-aminopropyl)-N-methyl-1,3-propanediamine was added, and the mixture was heated to 92-95℃ for chain extension polymerization. When the epoxy equivalent of the polymer reached 1100-1180 g / mol, the prescribed amounts of triglycidyl isocyanurate (e.g., model JF-810, epoxy equivalent 110 g / mol, purchased from Huangshan Jinfeng Industrial Co., Ltd.) and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane were added, and the mixture was heated to 100-103℃ for a secondary chain extension reaction. The polymerization continued until the amine value of the polymer reached 3m. When the KOH / g ratio is below a certain level, add low molecular weight E-20 epoxy resin with excellent adhesion (e.g., model E-20, epoxy equivalent of 527 g / mol, softening point of 67-73℃, purchased from Anhui Hengtai New Material Technology Co., Ltd.) and epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane. After stirring and mixing thoroughly at 100-103℃, remove a certain amount of solvent ethylene glycol monomethyl ether by vacuum distillation (e.g., vacuum degree controlled at -0.096 to -0.098 MPa) to control the solid content at 55-60 wt%. Then cool to room temperature to obtain epoxy adhesive for surface treatment, for later use. (2) Surface treatment of Teflon high-temperature cloth short fibers: Before preparing wood-plastic composite materials, the surface treatment adhesive prepared above is sprayed evenly with Teflon high-temperature cloth fibers at a mass ratio of 7-9:100. During the spraying process, the adhesive is stirred to ensure that the adhesive is fully mixed and uniform. Then, the fibers are vacuum dried (e.g., vacuum degree controlled at -0.096 to -0.098 MPa, drying temperature at 100-105℃). When the volatile content is less than 1wt%, the surface chemically treated Teflon high-temperature cloth short fibers are obtained and ready for use.

[0009] Preferably, the amount of component used in step (1) can be: 23-27 parts by weight of bisphenol A diglycidyl ether; 7-10 parts by weight of N-(3-aminopropyl)-N-methyl-1,3-propanediamine; 4-6 parts by weight of triglycidyl isocyanurate; 2-2.5 parts by weight of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 4-5 parts by weight of epoxy resin; 0.5-1 parts by weight of epoxy-based silane coupling agent; Solvent: 68-75 parts by weight of ethylene glycol monomethyl ether; The catalyst dosage is 0.1-0.2% of the mass of bisphenol A diglycidyl ether; The catalyst is triphenylphosphine, the epoxy resin is E-20 epoxy resin, and the epoxy silane coupling agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0010] Preferably, the high-toughness polyester resin used has an acid value of 28-33 mgKOH / g (e.g., high-toughness polyester resin of model GH-1271, Zhejiang Guanghua Technology Co., Ltd.). Its chains are soft and exhibit excellent toughness. As a plastic resin component, it has good compatibility with high-density polyethylene. Furthermore, the active carboxyl groups at the end of the polyester resin can undergo a cross-linking reaction with the epoxy adhesive components on the surface of the surface-treated Teflon high-temperature fabric fibers during the high-temperature molding and heat preservation stages, improving the adhesion and bonding effect between them, thereby achieving the effect of strengthening and toughening the high-density polyethylene plastic component. Preferably, it is pulverized and sieved into a fine powder of 100-120 mesh before use.

[0011] All other raw materials mentioned are commercially available or commonly used in the field. For example, the wood flour with a particle size of 80-100 mesh can be purchased from Lingshou County Derui Mining Co., Ltd.; the flame retardant filler is magnesium hydroxide or aluminum hydroxide with a particle size of 80-120 mesh; the maleic anhydride-grafted high-density polyethylene, with a maleic anhydride content of 1-1.3%, can be of model HD900E and can be purchased from Nanjing Huadu Technology Industry Co., Ltd.; the coupling agent can be N-2-aminoethyl-3-aminopropyltrimethoxysilane (KH-792).

[0012] In the above-mentioned formulation of this invention, a small amount of wood flour is mainly used to effectively fill the gaps inside the Teflon high-temperature cloth fibers during the processing of wood-plastic composite materials. The participation of high-toughness polyester resin, on the one hand, utilizes its own active carboxyl groups to cross-link and cure with the epoxy adhesive on the surface of the Teflon high-temperature cloth fibers, and on the other hand, utilizes its high-toughness chain segments to enhance the compatibility with high-density polyethylene. Maleic anhydride-grafted high-density polyethylene can not only utilize the carboxyl groups of maleic anhydride to cross-link with the epoxy adhesive on the surface of the Teflon high-temperature cloth fibers, but it can also effectively disperse the flame-retardant fillers in a uniform distribution within the system, increasing the compatibility of various fillers with high-density polyethylene resin. Melamine powder, as a flame-retardant cross-linking aid, can fully cure and shape the adhesive on the surface of the Teflon high-temperature cloth fibers during high-temperature molding and heat preservation, improving strength and flame-retardant properties. The extensive use of 1-2cm length Teflon high-temperature cloth fibers further enhances the strength of the wood-plastic composite material, ultimately resulting in a high-strength wood-plastic composite product.

[0013] The preparation method of the wood-plastic composite material includes the following steps: A. Mix the surface-treated Teflon high-temperature cloth fiber and wood flour in a mixer for 20-30 minutes. After the mixture is uniform, add the high-toughness polyester resin powder and flame-retardant crosslinking agent melamine powder and mix again for 5-10 minutes to form a mixed fiber material reinforced with wood flour, polyester and crosslinking agent for later use. B. Mix the formulated amount of mixed fiber material, high-density polyethylene, maleic anhydride-grafted high-density polyethylene, coupling agent and other various additives thoroughly at 140-145℃ for 15-25 minutes. After mixing evenly, discharge the material into a cold roller and cool it to 50-60℃ before discharging to make a special premix. C. Add the special premix obtained in step B to a conical twin-screw wood-plastic profile extruder for melt extrusion molding; for example, the process conditions are: barrel temperature of 210-215℃, screw speed of 25-35rpm; D. The extruded profiles are conveyed into the heat preservation section with the shaping mold by a conveyor belt for heat preservation to achieve full cross-linking and curing; for example, the heat preservation and curing time is 4-6 minutes and the heat preservation and curing temperature is 150-160℃. E. After the insulation is completed, the cured wood-plastic profile is cooled, shaped, and cut to a fixed length to obtain the finished product, which is the wood-plastic composite material.

[0014] The formulation described in this invention, as a whole, is prepared through the selection of specific surface-treated Teflon high-temperature fabric fibers, high-toughness polyester resin, wood flour, etc., and under specific processes. The prepared wood-plastic composite material exhibits good conventional properties, such as a smooth and flat surface, a static bending strength generally above 36 MPa, and indentations from drop ball impacts at room temperature generally 5.6 mm or less in diameter without breakage, indicating good impact resistance. Regarding freeze-thaw resistance, the surface is free of cracks and blistering, demonstrating excellent freeze-thaw resistance, indicating that the surface-treated Teflon high-temperature fabric fibers and the plastic components of this invention form a good integrated whole. Due to the significantly reduced wood flour content, the use of non-flammable and non-mold-prone Teflon high-temperature fabric fibers, and the increased cross-linking density, the flame-retardant and anti-mold effects are enhanced. Therefore, the flame-retardant performance of this invention is excellent; without the addition of external flame retardants and anti-mold agents, the oxygen index reaches above 35%, and the anti-mold rating reaches level 0.

[0015] Beneficial effects: The low-cost, high-strength wood-plastic composite material of this invention is obtained by mixing, extruding, and high-temperature setting raw materials including high-density polyethylene, high-toughness polyester resin, maleic anhydride-grafted high-density polyethylene, Teflon high-temperature cloth fiber material obtained through surface treatment, a small amount of wood flour, flame-retardant filler, coupling agent, and other additives. The Teflon high-temperature cloth fiber material obtained through surface treatment is obtained by cutting, crushing, and filtering Teflon high-temperature cloth scraps to obtain glass fiber material containing Teflon fibers with a length of 1-2 cm. Its main components are medium-alkali glass fiber (accounting for 90-93%) and a small amount of Teflon fiber (7-10%). Then, it is chemically treated with a specially prepared epoxy adhesive to obtain a fiber material with excellent bonding strength. The epoxy adhesive product used in this invention addresses the problem that Teflon high-temperature fabric fibers, due to their Teflon fiber content, have insufficient bonding strength and are prone to cracking when used with conventional adhesives. A semi-finished product is prepared by synthesizing and chain-extending bisphenol A diglycidyl ether with N-(3-aminopropyl)-N-methyl-1,3-propanediamine, triglycidyl isocyanurate, and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane. This semi-finished product is then compounded with a low-molecular-weight E-20 epoxy resin with excellent adhesion and the epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane. The high nitrogen content in this adhesive molecule not only enhances its flame retardant properties, but the presence of amino groups also strengthens the bond between the adhesive and Teflon fibers. The chain extension of triglycidyl isocyanate and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane increases the epoxy density of the adhesive, while the low molecular weight E-20 epoxy resin with excellent adhesion enhances the toughness and bonding strength of the adhesive. The participation of the epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane improves the wetting and bonding performance between the adhesive and the Teflon fiber surface.

[0016] In the formulation of the wood-plastic composite material of this invention, a small amount of wood flour and flame-retardant filler powder are mainly used to effectively fill the gaps inside the Teflon high-temperature cloth fibers during the processing of the wood-plastic composite material. The participation of high-toughness polyester resin is that, on the one hand, it utilizes its own active carboxyl groups to cross-link and cure with the epoxy adhesive on the surface of the Teflon high-temperature cloth fibers, and on the other hand, it utilizes its high-toughness chain segments to enhance the compatibility with high-density polyethylene. Maleic anhydride-grafted high-density polyethylene can not only utilize the carboxyl groups of maleic anhydride to cross-link with the surface adhesive of the Teflon high-temperature cloth fibers, but it can also effectively disperse the flame-retardant filler in a uniform distribution within the system, increasing the compatibility of various fillers with high-density polyethylene resin. Melamine powder, as a flame-retardant cross-linking aid, can fully cure and shape the adhesive on the surface of the Teflon high-temperature cloth fibers during the high-temperature molding process, ultimately obtaining a high-strength wood-plastic composite material product. Because this product uses a large amount of non-flammable and mildew-resistant Teflon high-temperature cloth short fiber material, the resulting wood-plastic composite material not only has high static bending strength, but also excellent flame retardant and mildew-resistant properties without the addition of additional flame retardants and mildew inhibitors. It is low in cost and realizes the comprehensive utilization of Teflon high-temperature cloth scraps, which has very important environmental and economic benefits.

[0017] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0019] Except for the brands explicitly stated below, the raw materials and reagents used in the examples are all conventional raw materials and reagents in the art.

[0020] High-density polyethylene, model 3000JE, was purchased from Maoming Branch of China Petroleum & Chemical Corporation; high-toughness polyester resin with an acid value of 28-33 mgKOH / g, model GH-1271, was purchased from Zhejiang Guanghua Technology Co., Ltd., and should be pulverized and sieved into a fine powder of 100-120 mesh before use; wood flour with a particle size of 80-100 mesh was purchased from Lingshou County Derui Mining Co., Ltd.; flame-retardant filler was magnesium hydroxide or aluminum hydroxide with a particle size of 80-120 mesh; maleic anhydride grafted polyethylene, model HD900E, was purchased from Nanjing Huadu Technology Industry Co., Ltd.; coupling agent was N-2-aminoethyl-3-aminopropyltrimethoxysilane (KH-792); lubricant was oxidized polyethylene wax with a dropping melting point of 94-100℃, model PEWO-0520, purchased from Nanjing Tianshi New Material Technology Co., Ltd.

[0021] Example 1 A low-cost, high-strength wood-plastic composite material, wherein the raw materials comprise, by weight: 24 parts of high-density polyethylene; 4.5 parts of high-toughness polyester resin; Nine parts of maleic anhydride-grafted polyethylene; 16 parts wood flour; 46 parts of surface-treated Teflon high-temperature cloth fiber; 4 parts of magnesium hydroxide, a flame-retardant filler; 0.7 parts coupling agent; 3 parts lubricant; The flame-retardant crosslinking agent melamine is used at a dosage of 0.5% of the Teflon high-temperature fabric fiber mass. When using melamine as a flame-retardant and reinforcing crosslinking agent, melamine can be ground into fine powder with a particle size controlled at 250 mesh.

[0022] Other additives include antioxidant 1010 and ultraviolet absorber UV-329, each in parts by weight of 0.5.

[0023] The preparation method of surface-treated Teflon high-temperature cloth fibers is as follows: Waste scraps of Teflon high-temperature cloth are first cut into sheets less than 10cm in length and width, then crushed and filtered to obtain short fiber materials with a length of 1-2cm and a fiber diameter of 8-15μm; then chemically treated. The chemical treatment method is as follows: (1) Preparation of adhesive: The prescribed amount of bisphenol A diglycidyl ether and catalyst were dissolved in the solvent ethylene glycol monomethyl ether, and then N-(3-aminopropyl)-N-methyl-1,3-propanediamine was added. The temperature was raised to 92-95℃ for chain extension polymerization. When the epoxy equivalent of the polymer reached 1100-1180 g / mol, the prescribed amount of triglycidyl isocyanurate (model JF-810, epoxy equivalent 110 g / mol, purchased from Huangshan Jinfeng Industrial Co., Ltd.) and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane were added, and the temperature was raised to 100-103℃ for a secondary chain extension reaction. When the amine value reaches below 3 mg KOH / g, add low molecular weight E-20 epoxy resin with excellent adhesion (e.g., model E-20, epoxy equivalent of 527 g / mol, softening point of 67-73℃, purchased from Anhui Hengtai New Material Technology Co., Ltd.) and epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane. After stirring and mixing thoroughly at 100-103℃, remove a certain amount of solvent ethylene glycol monomethyl ether by vacuum distillation (vacuum degree controlled at -0.096 to -0.098 MPa), and control the solid content at 55-60 wt%. Then cool to room temperature to obtain the adhesive for surface treatment, for later use. The dosage is: 27 parts by weight of bisphenol A diglycidyl ether; 8 parts by weight of N-(3-aminopropyl)-N-methyl-1,3-propanediamine; 6 parts by weight of triglycidyl isocyanurate; 2 parts by mass of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 4 parts by weight of E-20 epoxy resin; 1 part by weight of 3-(2,3-epoxypropoxy)propyltrimethoxysilane; Solvent: 70 parts by weight of ethylene glycol monomethyl ether; The catalyst is triphenylphosphine, and the amount used is 0.1% of the mass of bisphenol A diglycidyl ether; (2) Special surface treatment of Teflon high-temperature cloth short fibers: Before preparing wood-plastic composite materials, the surface treatment adhesive (solid content 58wt%) prepared above is sprayed evenly with Teflon high-temperature cloth fibers at a mass ratio of 8:100. During the spraying process, the adhesive is stirred to ensure that it is fully mixed and uniform. Then, it is vacuum dried (vacuum degree controlled from -0.096 to -0.098MPa, drying temperature is 105℃). When the volatile content is less than 1wt%, Teflon high-temperature cloth short fibers with surface chemical treatment are obtained and ready for use.

[0024] The preparation method of the wood-plastic composite material includes the following steps: A. Mix the surface-treated Teflon high-temperature cloth fiber and wood powder in a mixer for 30 minutes. After the mixture is uniform, add the high-toughness polyester resin powder and flame-retardant crosslinking agent melamine powder and mix again for 10 minutes to form a mixed fiber material reinforced with wood powder, polyester and crosslinking agent for later use. B. Mix the formulated amount of mixed fiber material, high-density polyethylene, maleic anhydride grafted polyethylene, coupling agent and other various additives at 145°C for 16 minutes. After mixing evenly, discharge the material into a cold roller and cool it down to 60°C before discharging to make a special premix. C. Add the special premix obtained in step B to a conical twin-screw wood-plastic profile extruder for melt extrusion molding; the process conditions are: barrel temperature of 215℃ and screw speed of 31rpm. D. The extruded profiles are conveyed into the heat preservation section with the shaping mold by the conveyor belt for heat preservation to achieve full cross-linking and curing; the heat preservation and curing time is 6 minutes and the heat preservation and curing temperature is 151℃. E. After the insulation is completed, the cured wood-plastic profile is cooled, shaped, and cut to a fixed length to obtain the finished product, which is the wood-plastic composite material.

[0025] Example 2 A low-cost, high-strength wood-plastic composite material, wherein the raw materials comprise, by weight: 27 parts high-density polyethylene; 5 parts of high-toughness polyester resin; 10 parts of maleic anhydride-grafted polyethylene; 18 parts wood flour; 51 portions of surface-treated Teflon high-temperature fabric fibers; 8 parts of flame-retardant filler aluminum hydroxide; 0.8 parts coupling agent; 4 parts lubricant; The flame-retardant crosslinking agent melamine is used at a dosage of 0.5% of the Teflon high-temperature fabric fiber mass. When using melamine as a flame-retardant and reinforcing crosslinking agent, melamine can be ground into fine powder with a particle size controlled at 220 mesh.

[0026] Other additives are antioxidant 1010 and ultraviolet absorber UV-329, each in parts by weight of 0.4.

[0027] The preparation method of surface-treated Teflon high-temperature cloth fibers is as follows: Waste scraps of Teflon high-temperature cloth are first cut into sheets less than 10cm in length and width, then crushed and filtered to obtain short fiber materials with a length of 1-2cm and a fiber diameter of 8-15μm; then chemically treated. The chemical treatment method is as follows: (1) Preparation of adhesive: The prescribed amount of bisphenol A diglycidyl ether and catalyst were dissolved in the solvent ethylene glycol monomethyl ether, and then N-(3-aminopropyl)-N-methyl-1,3-propanediamine was added. The temperature was raised to 92-95℃ for chain extension polymerization. When the epoxy equivalent of the polymer reached 1100-1180 g / mol, the prescribed amount of triglycidyl isocyanurate (model JF-810, epoxy equivalent 110 g / mol, purchased from Huangshan Jinfeng Industrial Co., Ltd.) and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane were added, and the temperature was raised to 100-103℃ for a secondary chain extension reaction. When the amine value of the material reaches below 3 mg KOH / g, add low molecular weight E-20 epoxy resin with excellent adhesion (e.g., model E-20, epoxy equivalent of 527 g / mol, softening point of 67-73℃, purchased from Anhui Hengtai New Material Technology Co., Ltd.) and epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane. After stirring and mixing thoroughly at 100-103℃, remove a certain amount of solvent ethylene glycol monomethyl ether by vacuum distillation (vacuum degree controlled at -0.096 to -0.098 MPa), and control the solid content at 55-60%. Then cool to room temperature to obtain the adhesive for surface treatment, for later use. The dosage is: 25 parts by weight of bisphenol A diglycidyl ether; 7 parts by weight of N-(3-aminopropyl)-N-methyl-1,3-propanediamine; 5 parts by weight of triglycidyl isocyanurate; 2.5 parts by weight of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 5 parts by weight of E-20 epoxy resin; 0.6 parts by weight of 3-(2,3-epoxypropoxy)propyltrimethoxysilane; Solvent: 72 parts by weight of ethylene glycol monomethyl ether; The catalyst is triphenylphosphine, and the amount used is 0.15% of the mass of bisphenol A diglycidyl ether; (2) Special surface treatment of Teflon high-temperature cloth short fibers: Before preparing wood-plastic composite materials, the surface treatment adhesive (solid content 56wt%) prepared above is sprayed evenly with Teflon high-temperature cloth fibers at a mass ratio of 8:100. During the spraying process, the adhesive is stirred to ensure that it is fully mixed and uniform. Then, it is vacuum dried (vacuum degree controlled from -0.096 to -0.098MPa, drying temperature is 100℃). When the volatile content is less than 1wt%, Teflon high-temperature cloth short fibers with surface chemical treatment are obtained and ready for use.

[0028] The preparation method of the wood-plastic composite material includes the following steps: A. Mix the surface-treated Teflon high-temperature cloth fiber and wood powder in a mixer for 20 minutes. After the mixture is uniform, add the high-toughness polyester resin powder and flame-retardant crosslinking agent melamine powder and mix again for 8 minutes to form a mixed fiber material reinforced with wood powder, polyester and crosslinking agent for later use. B. Mix the formulated amount of mixed fiber material, high-density polyethylene, maleic anhydride grafted polyethylene, coupling agent and other various additives at 140℃ for 20 minutes. After mixing evenly, discharge the material into a cold roller, cool it down to 60℃ and discharge it to make a special premix. C. Add the special premix obtained in step B to a conical twin-screw wood-plastic profile extruder for melt extrusion molding; the process conditions are: barrel temperature 215℃, screw speed 26rpm; D. The extruded profiles are conveyed into the heat preservation section with the shaping mold by the conveyor belt for heat preservation to achieve full cross-linking and curing; the heat preservation and curing time is 5 minutes and the heat preservation and curing temperature is 154℃. E. After the insulation is completed, the cured wood-plastic profile is cooled, shaped, and cut to a fixed length to obtain the finished product, which is the wood-plastic composite material.

[0029] Example 3 A low-cost, high-strength wood-plastic composite material, wherein the raw materials comprise, by weight: 21 parts of high-density polyethylene; 5 parts of high-toughness polyester resin; Nine parts of maleic anhydride-grafted polyethylene; 17 parts wood flour; 49 parts of surface-treated Teflon high-temperature cloth fiber; 7 parts of flame-retardant filler aluminum hydroxide; 0.8 parts coupling agent; 4 parts lubricant; The flame-retardant crosslinking agent melamine is used at a dosage of 0.6% of the Teflon high-temperature fabric fiber mass. When using melamine as a flame-retardant and reinforcing crosslinking agent, melamine can be ground into fine powder with a particle size controlled at 230 mesh.

[0030] Other additives include antioxidant 1010 and ultraviolet absorber UV-329, each in parts by weight of 0.45.

[0031] The preparation method of surface-treated Teflon high-temperature cloth fibers is as follows: Waste scraps of Teflon high-temperature cloth are first cut into sheets less than 10cm in length and width, then crushed and filtered to obtain short fiber materials with a length of 1-2cm and a fiber diameter of 8-15μm; then chemically treated. The chemical treatment method is as follows: (1) Preparation of adhesive: The prescribed amount of bisphenol A diglycidyl ether and catalyst were dissolved in the solvent ethylene glycol monomethyl ether, and then N-(3-aminopropyl)-N-methyl-1,3-propanediamine was added. The temperature was raised to 92-95℃ for chain extension polymerization. When the epoxy equivalent of the polymer reached 1100-1180 g / mol, the prescribed amount of triglycidyl isocyanurate (model JF-810, epoxy equivalent 110 g / mol, purchased from Huangshan Jinfeng Industrial Co., Ltd.) and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane were added, and the temperature was raised to 100-103℃ for a secondary chain extension reaction. When the amine value of the material reaches below 3 mg KOH / g, add low molecular weight E-20 epoxy resin with excellent adhesion (e.g., model E-20, epoxy equivalent of 532 g / mol, softening point of 67-73℃, purchased from Anhui Hengtai New Material Technology Co., Ltd.) and epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane. After stirring and mixing thoroughly at 100-103℃, remove a certain amount of solvent ethylene glycol monomethyl ether by vacuum distillation (vacuum degree controlled at -0.096 to -0.098 MPa), and control the solid content at 55-60%. Then cool to room temperature to obtain the adhesive for surface treatment, for later use. The dosage is: 23 parts by weight of bisphenol A diglycidyl ether; 6 parts by weight of N-(3-aminopropyl)-N-methyl-1,3-propanediamine; 4 parts by weight of triglycidyl isocyanurate; 2 parts by mass of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 5 parts by weight of E-20 epoxy resin; 1 part by weight of 3-(2,3-epoxypropoxy)propyltrimethoxysilane; Solvent: 68 parts by weight of ethylene glycol monomethyl ether; The catalyst is triphenylphosphine, and the amount used is 0.2% of the mass of bisphenol A diglycidyl ether; (2) Special surface treatment of Teflon high-temperature cloth short fibers: Before preparing wood-plastic composite materials, the surface treatment adhesive (solid content 60wt%) prepared above is sprayed evenly with Teflon high-temperature cloth fibers at a mass ratio of 7:100. During the spraying process, the adhesive is stirred to ensure that it is fully mixed and uniform. Then, it is vacuum dried (vacuum degree controlled from -0.096 to -0.098MPa, drying temperature is 100℃). When the volatile content is less than 1wt%, Teflon high-temperature cloth short fibers with surface chemical treatment are obtained and ready for use.

[0032] The preparation method of the wood-plastic composite material includes the following steps: A. Mix the surface-treated Teflon high-temperature cloth fiber and wood flour in a mixer for 27 minutes. After the mixture is uniform, add the high-toughness polyester resin powder and flame-retardant crosslinking agent melamine powder and mix again for 9 minutes to form a mixed fiber material reinforced with wood flour, polyester and crosslinking agent for later use. B. Mix the formulated amount of mixed fiber material, high-density polyethylene, maleic anhydride grafted polyethylene, coupling agent and other various additives at 145℃ for 24 minutes. After mixing evenly, discharge the material into a cold roller, cool it down to 60℃ and discharge it to make a special premix. C. Add the special premix obtained in step B to a conical twin-screw wood-plastic profile extruder for melt extrusion molding; the process conditions are: barrel temperature of 215℃ and screw speed of 33rpm. D. The extruded profiles are conveyed into the heat preservation section with the shaping mold by the conveyor belt for heat preservation to achieve full cross-linking and curing; the heat preservation and curing time is 4 minutes and the heat preservation and curing temperature is 160℃. E. After the insulation is completed, the cured wood-plastic profile is cooled, shaped, and cut to a fixed length to obtain the finished product, which is the wood-plastic composite material.

[0033] Example 4 A low-cost, high-strength wood-plastic composite material, wherein the raw materials comprise, by weight: 22 parts high-density polyethylene; 4 parts of high-toughness polyester resin; 8 parts of maleic anhydride-grafted polyethylene; 14 parts wood flour; 45 parts of surface-treated Teflon high-temperature cloth fiber; 5 parts of flame-retardant filler aluminum hydroxide; 0.6 parts coupling agent; 3 parts lubricant; The flame-retardant crosslinking agent melamine is used at a dosage of 0.4% of the Teflon high-temperature fabric fiber mass. When using melamine as a flame-retardant and reinforcing crosslinking agent, melamine can be ground into fine powder with a particle size controlled at 220 mesh.

[0034] Other additives include antioxidant 1010 and ultraviolet absorber UV-329, each in parts by weight of 0.4.

[0035] The preparation method of surface-treated Teflon high-temperature cloth fibers is as follows: Waste scraps of Teflon high-temperature cloth are first cut into sheets less than 10cm in length and width, then crushed and filtered to obtain short fiber materials with a length of 1-2cm and a fiber diameter of 8-15μm; then chemically treated. The chemical treatment method is as follows: (1) Preparation of adhesive: The prescribed amount of bisphenol A diglycidyl ether and catalyst were dissolved in the solvent ethylene glycol monomethyl ether, and then N-(3-aminopropyl)-N-methyl-1,3-propanediamine was added. The temperature was raised to 92-95℃ for chain extension polymerization. When the epoxy equivalent of the polymer reached 1100-1180 g / mol, the prescribed amount of triglycidyl isocyanurate (model JF-810, epoxy equivalent 110 g / mol, purchased from Huangshan Jinfeng Industrial Co., Ltd.) and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane were added, and the temperature was raised to 100-103℃ for a secondary chain extension reaction. When the amine value reaches below 3 mg KOH / g, add low molecular weight E-20 epoxy resin with excellent adhesion (e.g., model E-20, epoxy equivalent of 527 g / mol, softening point of 67-73℃, purchased from Anhui Hengtai New Material Technology Co., Ltd.) and epoxy silane coupling agent 3-(2,3-epoxypropoxy)propyltrimethoxysilane. After stirring and mixing thoroughly at 100-103℃, remove a certain amount of solvent ethylene glycol monomethyl ether by vacuum distillation (vacuum degree controlled at -0.096 to -0.098 MPa), and control the solid content at 55-60 wt%. Then cool to room temperature to obtain the adhesive for surface treatment, for later use. The dosage is: 26 parts by weight of bisphenol A diglycidyl ether; 8 parts by weight of N-(3-aminopropyl)-N-methyl-1,3-propanediamine; 6 parts by weight of triglycidyl isocyanurate; 2.5 parts by weight of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 4 parts by weight of E-20 epoxy resin; 0.8 parts by weight of 3-(2,3-epoxypropoxy)propyltrimethoxysilane; Solvent: 75 parts by weight of ethylene glycol monomethyl ether; The catalyst is triphenylphosphine, and the amount used is 0.16% of the mass of bisphenol A diglycidyl ether; (2) Special surface treatment of Teflon high-temperature cloth short fibers: Before preparing wood-plastic composite materials, the surface treatment adhesive (solid content 57wt%) prepared above is sprayed evenly with Teflon high-temperature cloth fibers at a mass ratio of 7:100. During the spraying process, the adhesive is stirred to ensure that it is fully mixed and uniform. Then, it is vacuum dried (vacuum degree controlled from -0.096 to -0.098MPa, drying temperature is 100℃). When the volatile content is less than 1wt%, Teflon high-temperature cloth short fibers with surface chemical treatment are obtained and ready for use.

[0036] The preparation method of the wood-plastic composite material includes the following steps: A. Mix the surface-treated Teflon high-temperature cloth fiber and wood powder in a mixer for 25 minutes. After the mixture is uniform, add the high-toughness polyester resin powder and flame-retardant crosslinking agent melamine powder and mix again for 9 minutes to form a mixed fiber material reinforced with wood powder, polyester and crosslinking agent for later use. B. Mix the formulated amount of mixed fiber material, high-density polyethylene, maleic anhydride grafted polyethylene, coupling agent and other various additives at 145℃ for 22 minutes. After mixing evenly, discharge the material into the cold roller and cool it down to 55℃ before discharging to make a special premix. C. Add the special premix obtained in step B to a conical twin-screw wood-plastic profile extruder for melt extrusion molding; the process conditions are: barrel temperature 215℃, screw speed 28rpm; D. The extruded profiles are conveyed into the heat preservation section with the shaping mold by the conveyor belt for heat preservation to achieve full cross-linking and curing; the heat preservation and curing time is 5 minutes and the heat preservation and curing temperature is 160℃. E. After the insulation is completed, the cured wood-plastic profile is cooled, shaped, and cut to a fixed length to obtain the finished product, which is the wood-plastic composite material.

[0037] Comparative Example 1 Other conditions are the same as in Example 1, except that the surface treatment of the Teflon high-temperature cloth fiber uses E-51 liquid epoxy resin (58% solid content) with the same solid content concentration instead of the adhesive used in this invention.

[0038] Comparative Example 2 Other conditions are the same as in Example 1, except that the high-toughness polyester resin in this invention is replaced with an equal mass of high-density polyethylene.

[0039] Comparative Example 3 Other conditions are the same as in Example 1, except that the amount of maleic anhydride-grafted polyethylene in this invention is reduced to 4 parts.

[0040] Comparative Example 4 Other conditions are the same as in Example 1, except that the flame-retardant crosslinking agent melamine is not used.

[0041] Comparative Example 5 Commercially available ordinary polyethylene wood-plastic composite material was used as a comparison (only wood flour was used as the fiber material, and the wood flour accounted for 55% of the wood-plastic composite material formula; Teflon high-temperature cloth fiber was not used). The comparison product was from our company.

[0042] Test method: The performance tests of the products of this invention are conducted according to the methods in GB / T 24508-2020 "Wood-Plastic Composite Flooring". Specifically, the freeze-thaw resistance test is conducted according to method 6.5.20 of GB / T 24508-2020 "Wood-Plastic Composite Flooring"; the static bending strength test is conducted according to method 6.5.3 of GB / T 24508-2020 "Wood-Plastic Composite Flooring"; the room temperature drop ball impact test is conducted according to method 6.5.4 of GB / T 24508-2020 "Wood-Plastic Composite Flooring"; the boiling water resistance test is conducted according to method 6.5.17 of GB / T 24508-2020 "Wood-Plastic Composite Flooring"; the flame retardant performance is tested by oxygen index according to GB / T2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test"; and the mildew resistance is tested according to QB / T2591-2003 "Test Methods and Antibacterial Effects of Antibacterial Plastics". The test data is shown in Table 1 below.

[0043] Table 1 Performance Comparison of Examples and Comparative Examples

[0044] As can be seen from Table 1 above, the wood-plastic composite materials prepared by the products of this invention (Examples 1-4) under specific processes and formulations exhibit good conventional properties. For example, the surface is smooth and flat, the static bending strength is generally above 36 MPa, and the diameter of the dents generated by falling balls at room temperature is generally 5.6 mm or less, with no breakage, indicating good impact resistance. In terms of freeze-thaw resistance, the surface is free of cracks and blistering, demonstrating excellent freeze-thaw resistance. This also indicates that the Teflon high-temperature cloth fibers after surface treatment and the plastic components of this invention form a good whole. Due to the significantly reduced wood flour content and enhanced cross-linking density in the products of this invention, the flame retardant and mildew-proof effects are also enhanced. Therefore, the flame retardant properties of the products of this invention are excellent, with an oxygen index of over 35% without the need for external flame retardants, and the mildew resistance level reaches 0.

[0045] In Comparative Example 1, E-51 liquid epoxy resin was used instead of the adhesive used in this invention. The adhesive's wetting ability, bonding strength, and functionality to Teflon high-temperature cloth fibers were all much lower than those of the specific adhesive product of this invention. The wood-plastic composite material product prepared was significantly lower than that of this invention in terms of impact resistance and freeze-thaw resistance. Comparative Examples 2 and 3 replaced the flexible polyester resin and reduced the amount of maleic anhydride-grafted polyethylene, respectively. The result was that the cross-linking degree between the Teflon high-temperature cloth fibers with the plastic components during the molding process was significantly reduced, the bonding force was worse, and the static bending strength and impact resistance were reduced to a certain extent. Moreover, the boiling water performance and freeze-thaw resistance were also significantly reduced. Comparative Example 4 did not use melamine, a flame-retardant crosslinking agent, which resulted in a certain degree of decrease in crosslinking density, a decrease in impact resistance and static bending strength, and a certain degree of reduction in boiling water resistance, freeze-thaw resistance, and flame retardancy.

[0046] Comparative Example 5 uses commercially available ordinary polyethylene wood-plastic composite material, which mainly uses high-density polyethylene and wood flour as the main raw materials. The wood flour fiber filler does not use Teflon high-temperature cloth fiber material. Due to the lack of additional adhesive treatment process, its product is inferior to the product of this invention in terms of static bending strength, impact resistance, and freeze-thaw resistance. In particular, its flame retardant performance is poor, with an oxygen index of only 26.9%. Moreover, the use of a large amount of wood flour results in poor mildew resistance.

[0047] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. A low-cost, high-strength wood-plastic composite material, characterized in that, By weight, the raw materials include: 22-27 parts of high-density polyethylene; 4-5 parts of high-toughness polyester resin; 8-10 parts of maleic anhydride-grafted high-density polyethylene; 14-18 parts wood flour; 45-51 parts of surface-treated Teflon high-temperature cloth fiber; 4-8 parts of flame-retardant filler; 0.5-0.8 parts of coupling agent; 3-4 parts lubricant; It also includes melamine, a flame-retardant crosslinking agent, used at a rate of 0.4-0.6% of the Teflon high-temperature fabric fiber mass; the lubricant is oxidized polyethylene wax.

2. The low-cost, high-strength wood-plastic composite material as described in claim 1, characterized in that, The raw materials also include other additives, such as one or two of antioxidants and ultraviolet absorbers, each in an amount of 0.3-0.5 parts by weight.

3. The low-cost, high-strength wood-plastic composite material as described in claim 1 or 2, characterized in that, The preparation method of surface-treated Teflon high-temperature cloth fibers is as follows: Waste scraps of Teflon high-temperature cloth are first cut into sheets with a length and width of less than 10cm. These sheets are then crushed and filtered to obtain short fiber materials with a length of 1-2cm and a fiber diameter of 8-15μm. These fibers are then chemically treated. The chemical treatment method is as follows: (1) Preparation of adhesive: Bisphenol A diglycidyl ether and catalyst are dissolved in ethylene glycol monomethyl ether solvent, and then N-(3-aminopropyl)-N-methyl-1,3-propanediamine is added. The temperature is raised to 92-95℃ for chain extension polymerization. When the epoxy equivalent of the polymer reaches 1100-1180 g / mol, the formulated amount of isocyanuric acid triglycidyl ester and N,N,N',N'-tetragoxypropyl-4,4'-diaminodiphenylmethane are added, and the temperature is raised to 100-103℃ for secondary chain extension reaction. When the amine value of the polymer reaches below 3 mg KOH / g, epoxy resin and epoxy silane coupling agent are added. After stirring and mixing thoroughly at 100-103℃, part of the solvent ethylene glycol monomethyl ether is removed by vacuum distillation. The solid content is controlled at 55-60%. Then the temperature is lowered to room temperature to obtain epoxy adhesive solution for surface treatment, which is ready for use. (2) Surface treatment of Teflon high-temperature cloth short fibers: Before preparing wood-plastic composite material, the epoxy adhesive solution prepared above and Teflon high-temperature cloth fibers are sprayed evenly at a mass ratio of 7-9:

100. During the spraying process, the mixture is stirred to ensure that it is fully mixed and uniform. Then, after vacuum drying, when the volatile content is less than 1wt%, Teflon high-temperature cloth short fibers with surface chemical treatment are obtained for later use.

4. The low-cost, high-strength wood-plastic composite material as described in claim 3, characterized in that, The chemical treatment method for surface-treated Teflon high-temperature fabric fibers, in step (1) of adhesive preparation, the amount of reactants used is: 23-27 parts by weight of bisphenol A diglycidyl ether; 6-8 parts by weight of N-(3-aminopropyl)-N-methyl-1,3-propanediamine; 4-6 parts by weight of triglycidyl isocyanurate; 2-2.5 parts by weight of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 4-5 parts by weight of epoxy resin; 0.5-1 parts by weight of epoxy-based silane coupling agent; Solvent: 68-75 parts by weight of ethylene glycol monomethyl ether; The catalyst dosage is 0.1-0.2% of the mass of bisphenol A diglycidyl ether; The catalyst is triphenylphosphine, the epoxy resin is E-20 epoxy resin, and the epoxy silane coupling agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

5. A low-cost, high-strength wood-plastic composite material as described in claim 1 or 2, characterized in that, The acid value of high-toughness polyester resin is 28-33 mgKOH / g. It is crushed and sieved into a fine powder of 100-120 mesh before use.

6. A low-cost, high-strength wood-plastic composite material as described in claim 1 or 2, characterized in that, When using melamine, a flame-retardant crosslinking aid, melamine should be ground into a fine powder with a particle size controlled at 200-250 mesh; the particle size of wood flour should be 80-100 mesh.

7. A low-cost, high-strength wood-plastic composite material as described in claim 1 or 2, characterized in that, The flame-retardant filler is magnesium hydroxide or aluminum hydroxide with a particle size of 100-120 mesh; the coupling agent is N-2-aminoethyl-3-aminopropyltrimethoxysilane.

8. The method for preparing the wood-plastic composite material according to any one of claims 1-7, characterized in that, Includes the following steps: A. Mix the surface-treated Teflon high-temperature cloth fiber and wood flour in a mixer for 20-30 minutes. After the mixture is uniform, add the high-toughness polyester resin and flame-retardant crosslinking agent melamine in the formula and mix again for 5-10 minutes to form a mixed fiber material reinforced with wood flour, polyester and crosslinking agent, for later use. B. Mix the formulated amount of mixed fiber material, high-density polyethylene, maleic anhydride grafted polyethylene, coupling agent and other additives thoroughly at 140-145℃ for 15-25 minutes. After mixing evenly, discharge the material into the cold roller and cool it to 50-60℃ before discharging to make a special premix. C. Add the special premix obtained in step B to a conical twin-screw wood-plastic profile extruder for melt extrusion molding; D. The extruded profiles are conveyed into the heat preservation section with the shaping mold by the conveyor belt for heat preservation to achieve full cross-linking and curing; E. After the insulation is completed, the cured wood-plastic profile is cooled, shaped, and cut to a fixed length to obtain the finished product, which is the wood-plastic composite material.

9. The method for preparing the wood-plastic composite material as described in claim 8, characterized in that, In step C, the melt extrusion molding process conditions are: barrel temperature of 210-215℃ and screw speed of 25-35 rpm.

10. The method for preparing the wood-plastic composite material as described in claim 8, characterized in that, In step D, the process conditions for heat preservation in the insulation section are: heat preservation curing time of 4-6 minutes and heat preservation curing temperature of 150-160℃.

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